Fiber reinforced hybrid composite winding core

ABSTRACT

A hybrid fiber reinforced polymer winding core consisting of several layers of different materials. The winding core layers are constructed so that structural reinforcing layers are sandwiched between outer protective layers. The outermost protective layer and innermost protective layer define the outer wall surface and inner wall surface of the winding core.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] Applicant claims the priority benefits of U.S. Provisional PatentApplication No. 60/472,608, filed May 22, 2003.

BACKGROUND OF THE INVENTION

[0002] This invention relates to web winding cores for use in windingweb material such as tissue paper, paper toweling, and the like. Moreparticularly, the invention is related to a fiber reinforced polymerwinding core.

[0003] The tissue making process entails winding the finished tissueproduct onto a cylindrical tube, commonly called a “core”. The core issupported by a mandrel that is inserted into the core. The mandrelrotates the winding core to a velocity with a surface speed that matchesthe linear speed of the tissue material moving through the end of thetissue machine. At the start of the winding process an adhesive istypically sprayed onto the winding core and the mandrel-driven windingcore is brought into contact with the moving tissue material, whichadheres to the winding core and begins to be wound onto the windingcore. When tissue winding is complete, the tissue material is cut andthe tissue-wound core is brought to a stop by the mandrel. A table orsimilar means is brought into support for the tissue-wound core and themandrel is extracted from the core. The tissue-wound core is then eithertransported to a storage facility or to a converting machine forconversion, i.e., unwinding, transverse perforation and rewinding intocommercial sized rolls.

[0004] In the storage facility, the tissue-wound core may be storedeither horizontally or vertically. On the converting machines, a plug isinserted into each end of the tissue-wound core. The tissue-wound coreis then raised by a mechanical hoist attached to the plugs and loweredinto the converting machine. In the converting machine, the plugssupport the tissue-wound core as it is rotated to unwind most of thetissue material that was previously wound onto the core. The lastseveral layers of tissue are discarded by cutting them off the core witha sharp knife. The knife often causes damage to the core. After theunwind operation, the core is transported back to the tissue machinewhere the winding process is repeated. During transportation, the coremay be handled manually or with handling equipment.

[0005] The vast majority of prior art winding cores used in tissuemaking and conversion are constructed from multiple layers of wood pulpfiber (sometimes called paper, board, core board or fiber) and glue thatare wound together in a spiral fashion to form a cylindrical tube. Fibercores can typically be reused on the order of 5-20 times before they aredamaged to such an extent that they are no longer usable. Damage to thefiber cores is most commonly caused by storage of the tissue-wound coreon its end. The end of the fiber core becomes distorted and crushed whenthe tissue-wound core is stored in a vertical orientation. After severalreuses, the fiber core can become so distorted that the winding corewill no longer fit over a mandrel or plugs will no longer fit into itsends. The fiber core is also commonly damaged through the cutting actionof the knife that is used to remove the scrap tissue at the end of anunwind operation. During each cutting procedure, the knife penetratesseveral layers of the fiber core and makes a deep cut over the entirelength of the core. After several reuses, the number of cuts becomesgreat enough that, when the winding core is rotated by the mandrel athigh velocity just before the start of a wind operation, the fiber coremay begin to delaminate and self-destruct. The integral wall thicknessof the fiber core must be such that the winding core can withstand thecentrifugal forces caused by high speed spinning and the structuralforces caused by the weight of the tissue roll that the winding coremust support.

[0006] In the prior art fiberglass composite cores have been utilized inwinding applications. However, for the large diameter cores used inwinding tissue materials, a typical fiberglass core with adequateresistance to crushing forces imparted by a wound roll weighsconsiderably more than fiber cores. While a fiber core may weigh onehundred pounds, a comparable fiberglass core will weigh from two hundredto three hundred pounds. This creates safety as well as handlingproblems. The fiberglass cores used in the prior art for windingapplications have been typically constructed from a number of layers ofresin impregnated glass fiber wound at a substantially constant angle,i.e., usually 50 to 60 degrees from the axial direction, throughout thewall thickness of the core.

SUMMARY OF THE INVENTION

[0007] The present invention provides a unique solution to the majordrawbacks of prior art winding cores. The invention disclosed is ahybrid fiber reinforced polymer core consisting of several layers ofdifferent materials that, when combined in a specific sequence and inspecific relative quantities, result in a winding core withcharacteristics superior to prior art cores. The invention winding coreweighs approximately the same as fiber cores, but has significantlyincreased crush strength, crush stiffness, bending strength, bendingstiffness, hoop strength, hoop stiffness, impact resistance, cutresistance, moisture resistance, and abuse tolerance. In summary, thepresent invention hybrid composite winding core has properties whichhave been specifically tailored to exhibit a high degree of stiffness,strength and resistance to abuse without increasing mass over the priorart. The present invention core is particularly useful when used inconjunction with large-scale tissue manufacturing operations.

[0008] These together with other objects of the invention, along withvarious features of novelty which characterize the invention, arepointed out with particularity in this disclosure. For a betterunderstanding of the invention, its operating advantages and thespecific objects attained by its uses, reference should be had to theaccompanying drawings and descriptive matter in which there isillustrated a preferred embodiment of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009]FIG. 1 is a side view, partly in section, of a winding coreconstructed according to the present invention.

[0010]FIG. 2 is a cross sectional side view of the portion of thewinding core shown in FIG. 1 as area 2.

[0011]FIG. 3 is a close up cross sectional view of an end cap.

[0012]FIG. 4 is a perspective view of a winding core with textured outersurface.

DETAILED DESCRIPTION OF INVENTION

[0013] Referring to the drawings in detail wherein like elements areindicated by like numerals, there is shown a winding core 10 constructedaccording to the principles of the invention. The invention exampleshown pertains to a core with a sixteen inch nominal inside diameterwith a nominal length of one hundred inches. A prior art fiber core ofthis size would typically require a wall thickness of betweenfive-eighths inches to three-quarters inches, and would weighapproximately one hundred pounds in order to provide adequate strength,stiffness and resistance to abuse. The invention winding core is notlimited to this particular core size, but applies to cores of virtuallyany size.

[0014] The winding core 10 of the present invention is constructed ofmultiple layers of polymer impregnated fibrous materials forming acylindrically-shaped, hollow winding core 10 with two open ends 2, awall 3 connecting both ends 2, said wall 3 having an exterior surface 4and an inner surface 5. The wall 3 is comprised of said layers. The walllayers are formed preferably through filament winding, but could also beformed other known manufacturing methods, including by hand by means ofa roll table. The winding core layers are constructed so that structuralreinforcing layers are sandwiched between outer protective layers. Theoutermost protective layer and innermost protective layer define theouter wall surface 4 and inner wall surface 5 of the winding core.

[0015] In a preferred embodiment shown in the drawings the winding corehas a wall comprised of nine layers, starting with the innermost layer11 to the outermost layer 19. The innermost 11 and outermost layers 19are comprised of a composition with a high percentage of polymer resin,i.e., approximately sixty to eighty percent. The innermost 11 andoutermost 19 layers act as sealers protecting the other layers fromfraying damage. The thickness of each of these layers, i.e., innermost11 and outermost 19, is approximately one hundredth to two hundredthinches in thickness. The outermost layer 19 defines the winding corewall exterior surface 4 and the innermost layer 11 defines the windingcore inner surface 5.

[0016] The next layers in, i.e., second layer 12 and eighth layer 18,are comprised of woven fiberglass cloth with approximately equal amountsof fiber in the warp and fill directions. These layers have a lowerresin content than the innermost 11 and outermost 19 layers. Thethickness of each of these layers, i.e., second layer 12 and eighthlayer 18, is approximately one hundredth to two hundredth inches inthickness and each contains approximately thirty to fifty percent resin.The second layer 12 and eighth layer 18 provide resistance to knife cutsand damage from core plugs.

[0017] The third through seventh layers 13-17 are the structural layersproviding resistance to longitudinal bending and radial crushing.Specifically, the third layer 13 and seventh layer 17 contain carbonfiber primarily oriented in the circumferential (hoop) direction. Thethird 13 and seventh 17 layers are each approximately one hundredth totwo hundredth inches in thickness and each contains approximately twentyto forty percent resin. The purpose of the third 13 and seventh 17layers is to provide extra resistance to crushing.

[0018] The fourth layer 14 and sixth layer 16 contain glass fibersoriented in the circumferential (hoop) direction. The fourth 14 andsixth 16 layers are each approximately three hundredth to six hundredthinches in thickness and each contains approximately twenty to fortypercent resin. The purpose of the fourth 14 and sixth 16 layers is toresist crushing.

[0019] The middle layer 15, i.e., fifth layer, contains glass fibersprimarily oriented in a longitudinal direction, i.e., parallel with awinding core longitudinal axis. The middle layer 15 is approximatelyfour hundredth to eight hundredth inches in thickness and containsapproximately twenty to forty percent resin. The purpose of the middlelayer 15 is to resist longitudinal bending. Although this layer isdescribed as the middle layer, it could actually be located at any layerposition and provide equivalent resistance to longitudinal bending.However, in the preferred embodiment this layer is centered as themiddle layer 15 within the wall thickness. In doing so, the crushingstiffness is maximized. If the fifth layer were placed at any otherlocation, the bending and hoop properties of the tube would not besignificantly changed, but the crush properties of the structure wouldbe significantly adversely affected.

[0020] Each layer is typically combined with wet resin, in thepercentage ranges indicated above, as the layer is wound over acylindrical tool commonly called a mandrel. After winding on themandrel, the resin is cured at an elevated temperature to initiatecross-linking and provide a rigid structure. The resin that is typicallyused is a Bisphenol F or Bisphenol A epoxy resin combined with ananhydride type hardener. Other types of epoxy resin/hardenerscombinations could work as well. The applicable resin systems include,but are not limited to, polyester resins, vinyl ester resins, phenolicresins, or other generally acceptable thermosetting resins suitable foruse with filament winding equipment. Thermoplastic resins could also beused with some modifications to manufacturing equipment. The core couldalso be made with pre-impregnated materials.

[0021] In another embodiment of the invention, a pre-manufacturedplastic or metal end cap 20 is mechanically or adhesively (or acombination of both) fastened to either end of the winding coreproviding further enhanced strength, stiffness and abuse resistanceproperties. In the example shown, the innermost 11, outermost 19, second12 and eighth layers 18 are removed near the winding core end to becapped, and the cap 20 slid over the end of the winding core wall. Apost-formed bead 22 may be formed on the outside portion 21 of the cap20 to mechanically attach the cap 20 to the winding core 10.

[0022] In another embodiment of the invention, a molded texture 9 couldbe formed on the outermost layer 19 of the winding core 10 to assist ingripping the tissue material during the start of a wind. The texturecould also be sprayed or painted on.

[0023] While the mass density of the invention winding core material istypically two to four times as great as that of a prior art fiber core,the invention winding core for the example described above only requiresa wall thickness of approximately one-fourth to one-half that of atypical fiber core. The invention core construction provides aresistance to both crushing and bending forces which is considerablygreater than that of a prior art fiber core. This results in a windingcore with superior crush and bending properties while weighingessentially the same as a prior art fiber core. Along with superiorcrush and bending properties comes substantially increased resistance toknife damage and abuse damage from winding and unwinding.

[0024] It is understood that the above-described embodiment is merelyillustrative of the application. Other embodiments may be readilydevised by those skilled in the art which will embody the principles ofthe invention and fall within the spirit and scope thereof. Asignificant portion of this invention are the layers that comprise thestructural portion of the winding core. These layers are identified withthe reference numerals as 13-17 in FIG. 2. The orientation and locationof the fibers is of paramount importance in these layers. It ispreferably to have the fibers that resist longitudinal bending locatedin the center of the wall thickness and the fibers that resist crushingforces located as near to the inner and outer wall surfaces as possible.The remaining layers are essentially protective layers, though they doadd a small amount of structural strength and stiffness.

[0025] Making the structural layers from a fiber reinforced material isa preferred choice because the properties of fibers are inherentlydirectional. Applicant has chosen to use primarily glass and carbonfibers in the example shown, but there are many other variable choices,including Kevlar, polyethylene, basalt, hemp, kenaf, and sisal, or otherorganic fibers.

[0026] The material that holds the fibers of a fiber reinforcedcomposite together is called the “matrix”. Applicants have chosen anepoxy resin as a preferred matrix. However, there are many othermaterials that could serve as the matrix for this invention includingother thermoset polymers like polyester or vinylester, or thermoplasticmaterials such as polyethylene.

I claim:
 1. A hybrid, fiber reinforced, polymer, web winding core foruse in winding web material, comprising: a cylindrical, hollow windingcore wall having two ends, said two ends defining a winding corelongitudinal axis, said wall having an exterior surface and an innersurface, said exterior surface and inner surface defining a wallthickness, said wall being comprised of a plurality of layers made fromfiber reinforced material, said plurality of layers having a pluralityof structural reinforcing layers sandwiched between a plurality of outerprotective layers, said plurality of structural reinforcing layersadapted to provide resistance to longitudinal bending and radialcrushing, said outer protective layers having an outermost protectivelayer defining the wall exterior surface and an innermost protectivelayer defining the wall inner surface.
 2. A winding core as recited inclaim 1, wherein: a plurality of the plurality of structural reinforcinglayers contains material with fibers primarily oriented in alongitudinal direction parallel with the winding core longitudinal axis,said layer adapted to resist longitudinal bending.
 3. A winding core asrecited in claim 2, wherein: a plurality of the plurality of structuralreinforcing layers contains material with fibers primarily oriented in acircumferential direction, said layers adapted to resist crushing.
 4. Awinding core as recited in claim 3, wherein: said plurality of layerscontaining material with fibers primarily oriented in a longitudinaldirection are located in the center of the wall thickness; and saidplurality of layers containing material with fibers primarily orientedin a circumferential direction are located near to the inner and outerwall surfaces.
 5. A winding core as recited in claim 4, furthercomprising: an end cap slidably positioned over and fastened to each endof the winding core wall.
 6. A winding core as recited in claim 5,further comprising: a molded texture formed on said outermost protectivelayer.
 7. A winding core as recited in claim 6, wherein: said fiberreinforced material is held in a matrix formed from the followingclasses of materials: thermoset polymers such as epoxy resins, polyesterresins, or vinyl ester resins, phenolic resins and thermoplastic resins.8. A winding core as recited in claim 7, wherein: said fiber reinforcedmaterial contain fibers made from the following classes of materials:glass, carbon, Kevlar, polyethylene, basalt, hemp, kenaf, and sisal. 9.A winding core as recited in claim 8, wherein: said plurality of layerscontaining material with fibers primarily oriented in a longitudinaldirection contain glass fibers in a matrix containing twenty to fortypercent resin.
 10. A winding core as recited in claim 9, wherein: aplurality of layers containing material with fibers primarily orientedin a circumferential direction contain carbon fibers in a matrixcontaining twenty to forty percent resin.
 11. A winding core as recitedin claim 10, wherein: a plurality of layers containing material withfibers primarily oriented in a circumferential direction contain glassfibers in a matrix containing twenty to forty percent resin.
 12. Awinding core as recited in claim 11, wherein: the outermost andinnermost protective layers are comprised of a composition with sixty toeighty percent polymer resin, said innermost and outermost protectivelayers adapted to act as sealers protecting the other layers fromfraying damage.
 13. A winding core as recited in claim 12, wherein: aplurality of protective layers being comprised of woven fiberglass clothwith approximately equal amounts of fiber in warp and fill directions,said protective layers containing thirty to fifty percent resin.
 14. Awinding core as recited in claim 13, wherein: a portion of said outerprotective layers are removed near the winding core end and said cappositioned over that portion of the winding core wall without the outerprotective layers.